The long term goals of this study are to understand the role of the Ke 6 gene in normal kidney function, to understand the mechanism of its involvement in the development of polycystic kidney disease (PKD), and to determine if Ke 6 can be used as a molecular tool to study the initiation and progression of cyst development in PKD. The specific aims of this proposal are as follows: 1. To characterize Ke 6 gene structure in order to understand exon/intron organization, to elucidate the alternative splicing mechanism which gives rise to Ke 6b mRNA and to understand the regulation of Ke 6 gene by examining the promoter region for specific regulatory elements. Ke 6 gene will be fully sequenced and mouse Ke 6b cDNA and human Ke 6 cDNAs will be isolated and sequenced by standard cloning techniques. 2. To determine the location of the Ke 6 gene expression in whole kidney section by in situ hybridization and at the cellular level by immunofluorescent techniques. This, along with the characterization of Ke 6 gene structure, will contribute to our understanding of the role of Ke 6 in normal kidney function. 3. To examine the pattern of aberrant regulation of the Ke 6 gene in polycystic kidney diseases. This will be pursued using Northern blot analysis, in situ hybridization of whole kidney sections and immunofluorescent studies either singly or in combination in congenital (cpk) and juvenile (jck) forms of heritable murine polycystic kidney disease (PKD), in cystogen-induced PKD in rats, and in different forms of human PKD. These experiments will facilitate understanding of the involvement of Ke 6 gene in the development of polycystic kidney disease.These studies will also determine the usefulness of Ke 6 as a molecular tool in the investigation of the initiation and progression of renal cysts especially since, our knowledge of the etiology and biochemical basis of cyst formation is limited. 4. To examine the mechanism of inhibition of Ke 6 gene expression in cpk and jck mouse. This will be done by Ke 6 promoter-CAT construct transfection analysis, DNase footprint analysis and electromobility shift assays. These experiments will be essential in understanding how the abnormal regulation of Ke 6 gene in murine PKD is effected by the primary defect in the cpk and jck genes. Investigating the role of Ke 6, a novel mammalian gene, in the development of PKD in mice should contribute to our understanding of PKD in humans and thus improve our ability to treat this disease effectively.